\documentclass{ctexart}
\usepackage{avanti}
\everymath{\color{Solarized-magenta}}
\pagestyle{empty} % 没有页眉和页脚

\tikzset{base/.style={smooth,thick,Solarized-base01}}
\tikzset{arrow/.style={->,>=stealth,base}}

\begin{document}

\begin{figure}[!ht]
    \centering
    \begin{tikzpicture}

        \draw [arrow] (0,0) -- (8.5,0) node[below] {};
        \draw [arrow] (0,0) -- (0,5) node[below] {};

        \draw [base,Solarized-yellow,domain=0.5:6.5] plot(\x,{0.08*(\x-0.2)^2+0.2});
        \draw [base,Solarized-blue,domain=0.5:6.5] plot(\x,{0.08*(\x-6.8)^2+0.2});
        \draw [base,Solarized-red,domain=0.5:6.5] plot(\x,{0.3*(\x-3.5)^2+2});

        \path (7.4, 0.3) node[Solarized-blue] () {经验风险};
        \path (7.4, 3.4) node[Solarized-yellow] () {置信区间};
        \path (7.4, 4.6) node[Solarized-red] () {泛化风险};
        \path (7.95, -0.3) node[Solarized-base01] () {VC维};

        \draw [base] (3.5,0) -- (3.5, 2.5);
        \draw [base,dashed] (5.5,0) -- (5.5, 4.0);
        \draw [base,dashed] (1.5,0) -- (1.5, 4.0);

        \path (3.5,-0.3) node () {$h^\star$};
        \path (1.5,-0.3) node () {$h_1$};
        \path (5.5,-0.3) node () {$h_t$};

        \draw [base] (2,-1.5) ellipse (0.6 and 0.3);
        \draw [base] (2.4,-1.5) ellipse (1.4 and 0.5);
        \draw [base] (2.8,-1.5) ellipse (2.2 and 0.7);

        \path (2.2,-1.5) node {$\Hcal_1$};
        \path (3.4,-1.5) node {$\Hcal^\star$};
        \path (4.6,-1.5) node {$\Hcal_t$};

        \draw [arrow] (1.7,-1.5) -- (1.5,-0.5);
        \draw [arrow] (2.8,-1.5) -- (3.3,-0.5);
        \draw [arrow] (4.0,-1.5) -- (5.2,-0.5);

    \end{tikzpicture}
\end{figure}


\end{document}